Spline width

Hi guys, I want to create a script which will store the "width" of a spline at it's nodes so I can approximately measure the width of a 3D racing track. I know that a spline doesn't actually have width, but I want to store a value of width at each node for when I export my spline data. I want to be able to create a line through each node, which I should be able to rotate and scale (so that I can measure the width more accurately) which will be used to store the nodes width. I've been told that the only real way for me to do something like this is to create a modifier which I can apply to normal splines, but have been told that this is pretty complex. Any help in getting this started?